Compressor-unloading mechanism



--'H. B. HALVORSEN.

COMPRESSOR UNLOADING MECHANISM.

APPLICATION man Amzz, 191s.

1,401,944., y y Patented m27, 1921.

retirant critics.

HALBERT B. HALVORSEN, OF CHICAGO, ILLINOIS, ASSIGNOR TO SULLIVAN MACHINERY COMPANY. A CORPORATION OF MASSACHUSETTS.

COMPRESSOB-UNLOADING lVECHAN-ISM.

Specification of Letters Patent.

)Patented Dec. 27, 1921.

Application filed April 22, 1919. Serial No. 291,819.

To (ZZZ iti/1.0m it may concern Be it known that I, Hammer B. I-IiirvonsnN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Compressor-Unloading Mechanism, of which the following is a full, clear, and exact specification.

My invention relates to compressors and pressure, IVhen this cylinder is unloaded,

that is, when itis not operating'to compress air, there is apt to 4be a slight leakage through the cylinder to the second stage c vlinder`of the compressor and this air which leaks through the first cylinder will be compressed in the second cylinder from about atmospheric pressure to a relatively7 high pressure with a resultant much greater rise in the temperature. For example, if a twostage compressor is used to compress air to 100 pounds and an intercooler is used between the stages of the compressor, the final temperature of the compressed air will be about 2430 F., if the air were compressed from about atmospheric pressure to 100 pounds pressure in the second stage only, the temperature would rise to about' i850 F. This high temperature might under some conditions be suthcient to explode combustible mixtures of oil and air which occur in the cylinders, due to the vaporization of the lubricating oil which is usually injected into the cylinders with the air to be compressed.

'Une object of the present invention is to provide an improved compressor unloading means especially applicable to one of the high-stages of a multi-stage compressor for unloading this'stage to prevent excessive temperatures therein and especially to prevent overheating when the lower stage is unloaded. Another object of the present invention is to provide an improved and simple unloading means which may easily be applied to any compressor 'and which is composed of a very few parts which are easily assembled and in which t-he wear is reduced to a minimum. These and other objects and advantages of my improvement will, however, Yhereafter more fully appear.

In the accompanying drawings, I 4have shown for Ipurposes lof illustration, one embodiment which my invention may assume in practice.

In these drawings,-

Figure 1 is a side elevation of a two-stage compressor provided with my improved unloading means.

Fig-2 is a. longitudinal sectional view through the unloading means.

In this illustrative construction, I have shown my invention applied to the high pressure cylindger of a two-stage compressor having a low pressure cylinder 1 and a high pressure cylinder 2 connected lin a well known manner by an intercooler 3, these parts being preferably mounted upon a base 4. The `air or other iuid to be compressed is drawn in through an inlet 5 having therein an unloading 'means 5 which may be of' any of a number of well known types, the air entering the lowpressure cylinder through inlet valves 6 and being forced from this cylinder into the intercooler 3Y through discharge valves 7, these valves being preferably of the automatic spring operated type, although i-f desired any other type of valve may be used'. The air compressed in 'the primary cylinder 1 is first cooled in the intercooler 3 and is then drawn into the high pressure cylinder 2 through rior of the cylinder itself. Referring more y particularly to Fig. 2, it will be seen that my unloading means is connected with the interior of the cylinder by means of a short pipe 12, which conducts the pressure fluid from the interior of the cylinder to an annular space 13 in the casing 14 of the unloading mechanism 10 and that the compressed air or other fluid in the pipe line 12 and annupipe 11 when these passages are placed'in lar space 13 Awill 4be exhausted through the longitudinal passageway 15. to the exhaust communication by proper valve mechanism. It will be understopd that the pipe 12 communicates with the compression space of the cylinder 2 at such point as to subject the thermostatic control means to thehighest temperatures produced during compression.

In the form of my improvement shown herein, this valve' mechanism comprises a valve` stem 16 herein shown as hollow, carrying on one end'thereofa valve head 17 adapted to seat against the valveseat 18 to close communication between the passages 13 and 15. I have also provided -a valve stem guiding means herein shown` in theform of fins or wings 19 carliedbyjgthe valve stem in engagement with the casing 14, butas is obvi' ous, these wingsmay be formed on the casing and engagei'the'valve stem 16 to guide `the latter. Thevalve stem 16 and the casing 14 are preferablyA formed of different' materials having different coeiicients of heat ex pansion, the stem 16 hprefprably having the lower noeiicient'of expansion and the wings 19 yare so formed thatthe fluid vcompressed inthe'cylinders `and forced into the valve casing 14 will flow into the space between the valvestem lfand the casing 14l so that this stem and casing will be subjected/to the heatl seat 18 permitting the exhausting of the high pressure cylinder through pipe 12, an nularspace 13, and passagewaylto the exhaust pipe 11 thereby. reducing the pressure and the temperature in the :high pressure cylinder.

`Since the contraction ofthe casing 14 during a decrease of temperature may force the lvalve head 17 against the valve seat 18 with apressure suiiicient to injure some of the valve mechanism, I preferably provide a4 lost 4motion connection between the valve stem 16 and the' valve casing 14. In the form oi my improvement shown herein, this lost motion` connection consists of a valve rod20 having threaded connection as shown at 21 with the valve stem 16 and passing centrally, through a guiding and adjusting plug V2,2 in the end.

of the casing 13, the outer end of the valve rod 20 preferably being threaded as shown at 23 to receive a nut 24 which engages the adjusting plug 22. A spring 25 is also preferably provided .to ,normally seat `the valvev head against the valve seatv 18, but if the casing 14 should contract to such an extent as to tend to force the valve head against the seat with an undue pressure, the valve spring 25 will be compressed and thereby relieve the valve mechanism of any excessive strain. As is apparent, the valve stem may be adjusted in relation to thevalve casing 14 through a movement of the plug 22 with relation to the casingf14 or of the nut 24 on the threaded endf23 of .the valve rod 20, thereby permitting an adjusting of the spring tension and an adj ustment in the movement of thevalve stem 16.

Since there is a wide range of variation between the temperatures generated in the iirst stage of a 1multi-s tage compressor, and in the final stage of a `multistage compressor when the latter'is operating to compress air from atmospheric pressureto inal pressure, 'the thermostatic unloading mechanism may easily be set to relieve the pressure in the high pressure cylinder at some point below that at which a combustible mixture in the high pressure stage would be ired. This thermostatic device may be rendered as sensif tiveas desiredby' forming the valve casing 14 and the .valve stem 16of relatively thin material so that theywill respond almost-in,- stantly to temperature variationsy and if desired,the casing 14 vmay be insulated with' any Vsuitable heat insulating material as an asbestos covering 14 to prevent the radia-4 tion of heat Jfrom this valve member.

It will'be noted that my thermostatic unV loading'meansis composed of a very few 1 parts which require a.- minimum amount of -machining, that this mechanism may be applied to anycompressor with a very slight change-in compressor construction, zn'. e., the boringof a hole into the interior of the cylinder itself, and that the parts ofthe mechanism are' easily assembled, adjusted, and repaired. It will further be noted that this mechanism is positively operating, is not composed of any delicate parts, and may be very chea ly manufactured.

While in'have in this application specifi-l cally described ,one embodiment which my 'invention may assume in practice, it 1s to be understood that this form is shown for illustrative purposes only, and that the invention may be modified and ambodied in various other forms without departing from its spirit Yor the scope of theappended claims.

' What I claim as new and desire to secure V'by Letters Patent is:

1. In a compressor, in combination, a thermally operated unloading means comprising y 12o 4 discharging pressure fluid from said casing controlled by said valve. y

2. In aI compressor, in combination, a ther'- .mally operatedunloading means comprising a plurality of concentrically disposed mem bers having diiierent coefficients of heat expanson,V the outer one of said members constituting a casing, and means for continuously admitting the compressed medium between said members.

3. In a compressor, in combination, a thermally operated unloading means comprising a plurality ot' membershaving different coefficients of heat expansion, and a lost motion connection between two of said members.

4. In a compressor, the combination with a compression chamber, of a thermally operated unloading means mounted adjacent one end of the compression chamber, and means for maintaining a constant communication between said means and the interior of said chamber.

5. In a compressor, the combination with a compression chamber, of a thermally operated unloading means therefor Vcomprising a relief valve operative directly to vent said chamber, and thermal controlling means for the latter disposed in constant communication with a portion of said chamber in which the maximum heat of compression is produced.

G. In a compressor, the combination with a compression chamber, of thermally operated unloading means mounted adjacent each end ot' the compression Achamber and exposed directly to the maximum temperatures produced during compression.

7. In a compressor, the combination with a compression chamber, ofunloading means therefor comprising al relief valve operative when opened to permit. the discharge of fluid at pressures less than normal compressor discharge pressure, and means for controlling the operation ofsaid valve including heat responsive means' in constant communication with said compression chamber.

8. In a compressor, in combination, an unloading means including a member having one coetlicient ot heat expansion, .a second member having a different coeiiicient of heat expansion, a valve element connected to said first named member, and a second valve element connected to said second named member, one of said valve elements being movable relative to the other element upon a change in temperature.

.9. In a compressor, in combination, an unloading means including a member having one coeihcient of heat expansion, a second member therein having a diilerent coefficient ot' heat expansion, a. valve element connected to said first named member, and a second valve element connected to said second named member, one of said valve elements being movable relative to theother element upon a change in temperature.

10. In a compressor, in combination, an unloading means including a member having one coefficient ot heat expansion, a second member having a different coefficient to said irst named member, and a second valve element connected to said secondl named member by a lost motion connection, one of said valve elements being movable relative to the other element upon a change in temperature.

11. In a compres-aol', in combination, an unloading means includin-ga member having one coeliicient of heat expansion, a second Inember having a different coetiicicnt ot heat expansion, a valve element connectedy vto said til-st named member, and a second valve element connected to said second named member by an adjustable lost motion connection, one ot' said valve elements being movable relative to the other elementfupon a change in temperature. f

12. In a compressor, in combination, an unloading means including a member having one coefficient of heat expansion, a second member having a different coeiiicient of heat expansion, a valve element connected to said first named member, and a second valve element connected to said second named me'mber by an adjustable spring pressed lost motion connection, one of said valve elements being movable relative to the other element upon a change in temperature.

13. Ina compressor, in combination, an unloading means including a member having one coeiiicient of heat expansion, a second member having a diiierent coetlicient of heat expansion, a valve seat connected to said first named member, and a second valve element connected to said secondnamed member and adapted to cooperate with said seat, one of said valve elements being movable relative to the other element upon a change in temperature.

14:. In a compressor, in combination, an unloading means including a member having` one coefficient of heat expansion, a second member having a different coetlicient of heat expansion, a valve seat connected to said first namedmembenand a second valve element connected to said second named member by a lost motion connection and adapted to cooperate with said seat, one of said valve elements being movable relative to the other element upon a change in temperature.

15. In a compressor,V in combination, an unloading means including a member having one coefficient of heat expansion, a second member therein spaced therefrom having a diHerent coefiicient of heat expansion., guiding means between said members, a seat on one of said members, a cooperating valve head on the other of said members, and means for supplying fluid from said com- -pressor to the space between said members,

said valve head being moved from and toward said seat upon increase or decrease respectively in the temperature of said fluid.

from said compressor to the vspace between 1 16. In a compressor, in combination, an unloading means including a'vmember having one coefficient of heat expansion, a seoond membertherein 'spaced therefrom having a different oo efiicient of heat expansion,

guiding means between said' members, an adjustable lost motion connection between said members, a seatl on one of said members, l a coperating valve head on the other of said members, and means for supplyingluid said members, said valve head beingrl'noved from and toward said seat upon increase or decrease respectively in said fluid.,

17. In combination, a compressor,` an unloading Valve therefor, thermostatio conthe temperature of .trolling means for effecting opening o`f said valve von rise of temperature, and means HALBERTB. HAILVo-RsEN. 

